A USB to I²C bridge reference guide (PDF!) from Microchip:
Microchip’s SCSI USB to I²CTM bridge devices provide a USB to I²C bridge. The I²C bridge utilizes SCSI pass-through
commands using the Mass Storage Class driver. The internal hub can have e.g., three ports enabled with two exposed
externally. This document includes the following topics:
• Example of a USB to I²C Bridge Environment on page 1
• SCSI Pass-through Commands on page 3